Astronomers Announce 12 Previously Undiscovered Jupiter Moons

July 17, 2018, 10:44 PM UTC

Astronomers have discovered 12 more moons orbiting Jupiter, bringing the total to 79.

The International Astronomical Union, the worldwide authority on recognizing celestial bodies, published on Tuesday the orbits for Jupiter’s new moons, which were identified by a team of astronomers at the Carnegie Institution for Science in Washington DC.

None of the new moons are more than 2 miles in diameter, which explains why they have not been noticed before. The astronomers detected them by using a powerful telescope in Chile that was designed to detect faint objects in space.

Scott Sheppard, who led the team, said that the moons were spotted almost by accident. The team of astronomers, which in 2014 discovered the furthest known object orbiting the sun, had been looking for other objects on the fringe of our solar system.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System,” Sheppard said.

Two of the new moons orbit Jupiter closer to the planet than the others, moving in the same direction as its spin rotation. Nine more are part of a distant outer swarm of moons that move in the opposite direction of Jupiter’s rotation.

The last moon is an “oddball,” according to Sheppard’s team, because it has an orbit like no other known Jovian moon. That moon, named Valetudo after Roman goddess of health and hygiene, is also in the outer swarm but moves in the opposite direction of its peers.

Valetudo’s idiosyncratic path increases the likelihood that it will one day stray into the path of another moon and collide with it. “This is an unstable situation,” Sheppard said. “Head-on collisions would quickly break apart and grind the objects down to dust.”

The moons were discovered a year ago, but the IAU typically requires a year of calculations to confirm the existence of newly discovered moons.